U.S. patent application number 13/661818 was filed with the patent office on 2013-11-21 for flue-gas desulfurization equipment.
The applicant listed for this patent is Takeshi KIMURA. Invention is credited to Takeshi KIMURA.
Application Number | 20130309139 13/661818 |
Document ID | / |
Family ID | 49581456 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130309139 |
Kind Code |
A1 |
KIMURA; Takeshi |
November 21, 2013 |
FLUE-GAS DESULFURIZATION EQUIPMENT
Abstract
In flue-gas desulfurization equipment, in order to gypsumize
sulfur dioxide in a byproduct at approximately 100% and to make
desulfurization rate approximately 100%, the flue-gas
desulfurization equipment (1) according to the present invention is
provided with a basket-shaped rotation cylinder (20) arranged in
the fixing duct (10) in a state of being supported rotatably around
a horizontal shaft (21), a rotation packed bed (30) formed by
filling fillers for gas-liquid contact in the basket-shaped
rotation cylinder (20), a slurry storage tank (40) having plural
communication storage sections (41) located below the rotation
packed bed (30) and divided by separation plates (43) each of which
has a communication part (43a), and slurry spraying means (63)
which are provided corresponding to the plural communication
storage sections (41) and which spray the absorbent slurry
extracted from the corresponding communication storage sections
(41) to upper parts of the communication storage section (41) in
the rotation packed bed (30) respectively.
Inventors: |
KIMURA; Takeshi; (Mito-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KIMURA; Takeshi |
Mito-shi |
|
JP |
|
|
Family ID: |
49581456 |
Appl. No.: |
13/661818 |
Filed: |
October 26, 2012 |
Current U.S.
Class: |
422/106 ;
422/181 |
Current CPC
Class: |
B01D 2251/404 20130101;
B01D 53/504 20130101 |
Class at
Publication: |
422/106 ;
422/181 |
International
Class: |
B01D 53/78 20060101
B01D053/78; G05D 9/00 20060101 G05D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2012 |
JP |
2012-111978 |
Claims
1. Flue-gas desulfurization equipment characterized by being
provided with a fixing duct formed with a specific length having a
gas introduction inlet at one side and a gas discharge outlet at
another side; a basket-shaped rotation cylinder formed
approximately cylindrically whose both end surfaces and a
peripheral surface are formed in reticulated pattern or lattice
pattern, wherein said end surface at one side faces the gas
introduction inlet and said end surface at another side faces the
gas discharge outlet, and which is located in the fixing duct in
the condition of being supported rotatably around a horizontal
shaft; a rotation packed bed which is constituted of filling
fillers for gas-liquid contact in the basket-shaped rotation
cylinder and through which gas introduced from a gas introduction
inlet flows in an axial direction thereof; gas shield plates
arranged at a gas introduction inlet side and a gas discharge
outlet side of the rotation packed bed; a slurry storage tank
located below the rotation packed bed and having plural
communication storage sections which are divided by partition
plates each of which has a communication part at a portion thereof;
a slurry feed means for feeding absorbent slurry to a gas discharge
outlet side in the slurry storage tank; a slurry discharge means
for discharging the absorbent slurry from a gas introduction side
in the slurry storage tank; and slurry spray means which are
provided in response to the plural communication storage sections
respectively and each of which sprays the absorbent slurry
extracted from the corresponding communication storage section to
an upper part of the communication storage section of the rotation
packed bed, wherein the plural communication storage sections are
arranged so as to line up along the axial direction, and wherein
the absorbent slurry which is fed to the gas discharge outlet side
in the slurry storage tank by the slurry feed means moves through
the plural communication storage sections to the gas introduction
inlet side with desulfurization and gypsumization and discharges
from the gas introduction inlet side in the slurry storage
tank.
2. Flue-gas desulfurization equipment according to claim 1,
characterized by being provided with an independent storage section
divided by a separation plate without the communication part in the
slurry storage tank; a liquid level control means for feeding
absorbent slurry to the independent storage section so as to hold a
specific liquid level thereof; and a slurry spray means for
spraying the absorbent slurry extracted from the independent
storage section to an upper part of the independent storage section
in the rotation packed bed, wherein the independent storage section
is positioned at the gas discharge outlet side of the plural
communication storage sections, and wherein the slurry feed means
feeds the absorbent slurry extracted from the independent storage
section to the communication storage section of the plural
communication storage sections positioned the closest to the gas
discharge outlet side, so that feed of the absorbent slurry can be
controlled.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to flue-gas desulfurization
equipment (hereinafter, FGD equipment) for removing sulfur dioxide
from gas exhausted from factories or electrical power plants,
especially to a FGD equipment which can reduce slurry circulating
volume and draft pressure loss leading to energy consumption, which
has approximately 100% of desulfurization rate by assuming a case
of installing it as a preceding step of a device for recovering
carbon dioxide gas which is installed sometime in the future and
which can make byproducts gypsum at approximately 100%.
[0002] In the past, the FGD equipment removing sulfur dioxide gas
from processed gas by flowing adsorbent slurry down in vertical
direction in a cylindrical casing and by flowing the processed gas
therein is known.
[0003] Especially in Japan, the FGD equipment whose system uses a
vertical type of a cylindrical body and makes the processed gas
flown vertically is used widely.
[0004] However, in the FGD equipment whose system uses the vertical
type of the cylindrical body, there is problem such that energy
consumption becomes large as slurry circulating volume is
increased. Concretely, in the FGD equipment, since gas throughput
is increased with the square of a diameter of the cylindrical body,
the circulating volume of the slurry being absorbent is increased
with the square of the diameter of the cylindrical body.
[0005] On the other hand, though an exhaust desulfurizer whose
system is to flow the processed gas in horizontal direction by
using a horizontally cylindrical body arranged so as for a rotation
shaft to extend in horizontal direction is similar to the FGD
equipment using the vertically cylindrical body in point that the
gas throughput is increased with the square of the diameter of the
cylindrical body, the slurry circulating volume is increased only
in direct proportion to the diameter of the cylindrical body.
[0006] Accordingly, without pausing to image a linear expression
graph and a quadratic expression graph, because the slurry
circulating volume in the case of using horizontally cylindrical
body is less than one in the case of using vertically cylindrical
body and the energy consumption is less, so that it is advantageous
to use the horizontally cylindrical body. Especially in a large
type of the FGD equipment, as a cylindrical body becomes larger, it
is remarkably advantageous to use the horizontally cylindrical body
rather than to use the vertically cylindrical body.
[0007] Besides, the reason that the FGD equipments using the
vertically cylindrical body are used widely in Japan is thought to
be due to applying attitude of a gas adsorption device developing
based on an original small size device to the FGD equipment being a
large size device.
[0008] For instance, what are shown in Japanese utility model
publication No. sho 53-19171 and Japanese patent No. 4418987 (U.S.
Pat. No. 7,527,679B2/CN 101099922B) are known as the FGD equipment
using the horizontally cylindrical body.
[0009] Japanese utility model publication No. sho 53-19171 is that
a lot of lifters or troughs consisting of U-shaped tubs for
scooping up desulfurizing agent are provided in parallel to axial
direction on an inner wall of a rotation cylinder with an annular
end plate having a processed gas inlet port at one end thereof and
an annular end plate having an outlet port at the other end
thereof, and the rotation cylinder in which a lot of separated
fillers having apertures or holes are filled in a whole internal
space is arranged horizontally and rotatably, and a means for
supplying absorption slurry is provided at one end of the rotation
cylinder and an outlet of the slurry is discharged at the other end
of the rotation cylinder.
[0010] In this FGD equipment, while the fillers positioned at a
lower part are immersed in the slurry retained below of the
rotation cylinder, the rotation cylinder is rotated so as to bring
the processed gas into contact with the absorption slurry in
countercurrent flow or in parallel flow, so that gas-liquid contact
can be achieved.
[0011] As an actual achievement of working the FGD equipment
described in Japanese utility model publication No. sho 53-19171,
there are a prototype machine with 1 m diameter of the rotation
cylinder (a rotation packed bed), a first practical machine with
3.2 m diameter of the rotation cylinder, a second practical machine
with 4.5 m diameter of the rotation cylinder and a third practical
machine with 4.5 m diameter of the rotation cylinder, and all of
them are successful, and especially the first and the second
practical machine have approximately 40 years operation
performance. Here, they have 3 m length in axial direction of the
rotation cylinder. Besides, if considering that byproducts are
calcium sulfite, the length of the rotation cylinder can be made
shorter (approximately by 1 m).
[0012] The succession of these machines is to support the above
opinion such that "it is remarkably advantageous to use the
horizontally cylindrical body rather than to use the vertically
cylindrical body in the FGD equipment being a large device".
[0013] The operation performance of every machine is shown in Table
1:
TABLE-US-00001 TABLE 1 Gas Slurry Throughput Diameter Length
Circulating (Nm.sup.3/h) (m) (m) Volume (m.sup.3/h) Prototype
Machine 5,000 1 3 150 First Practical 60,000 3.2 3 480 Machine
Second Practical 90,000 4.5 3 675 Machine Third Practical 90,000
4.5 3 675 Machine
[0014] As shown in Table 1, the slurry circulating volume is
increased only in direct proportion to the diameter of the
cylindrical body in each machine, it is understood that "it is
remarkably advantageous to use the horizontally cylindrical body
rather than to use the vertically cylindrical body in the FGD
equipment being a large device".
[0015] Thus, in the FGD equipment described in Japanese utility
model publication No. sho 53-19171, about the slurry circulating
volume, it should be noted that circulating volume of the slurry
must be considered in proportion to the diameter of the rotation
cylinder.
[0016] Furthermore, as shown in Table 1, every machine has 3 m
length in the axial direction of the rotation cylinder (the
rotation packed bed), and this shows it is advantageous to use the
horizontal cylinder rather than to use the vertical cylinder in the
case that the diameter of rotation cylinder becomes more than 3
m.
[0017] Here, it is another factor that should not be overlooked
that the larger the diameter of the rotation cylinder, the larger
the dropping height of the slurry in proportion to the diameter of
the rotation cylinder. Namely, chemical reaction quantity
associated with once dropping of the slurry is 3.2 times in the
case of 3.2 m diameter of the rotation cylinder, and 4.5 times in
the case of 4.5 m diameter of the rotation cylinder, based on the
case of 1 m diameter of the rotation cylinder. Accordingly, in the
case of a fourth trial designed machine as will become apparent
below, as the diameter of the rotation cylinder is 24.3 m, the
chemical reaction quantity associated with once dropping of the
slurry becomes 24.3 times.
[0018] This may be thought for it to be a root that it is
advantageous to flow the gas horizontally rather than to flow the
gas vertically.
[0019] On the other hand, operation of the FGD equipment described
in Japanese utility model publication No. sho 53-19171 is, in an
aspect of chemical reaction, to produce gypsum as a byproduct by
using limestone slurry as an absorbent for sulfur dioxide. In this
case, process such that calcium sulfite is produced as a medium
product, and then, the calcium sulfite is oxidized by oxygen in the
processed gas (exhaust gas) to be gypsum is carried out.
[0020] For the process for gypsumization of the calcium sulfite, it
was known that there is delicate relation between oxygen
concentration in the processed gas and pH of the gypsum slurry
discharged from the device.
[0021] Arranging knowledge about the process of gypsumization of
the calcium sulfite as mentioned above, it is considered as
follows.
SO.sub.2+H.sub.2O.fwdarw.H.sub.2SO.sub.3 (1)
CaCO.sub.3.fwdarw.Ca.sup.2++CO.sub.3.sup.2- (2)
Ca.sup.2++H.sub.2SO.sub.3.fwdarw.CaSO.sub.3+2H.sup.+ (aqueous
calcium sulfite) (3)
CO.sub.3.sup.2-.fwdarw.CO.sub.2+1/2O.sub.2 (4)
CaSO.sub.3+1/2H.sub.2O.fwdarw.CaSO.sub.3.1/2H.sub.2O (crystalline
calcium sulfite) (5)
CaSO.sub.3+1/2O.sub.2+2H.sub.2O.fwdarw.CaSO.sub.4.2H.sub.2O (gypsum
crystal) (6)
[0022] In acid slurry in a slurry outlet side (a gas introducing
inlet side), crystalline calcium sulfite is dissolved, and reaction
shown in the following formula (7) is undergone.
CaSO.sub.3.1/2H.sub.2O.fwdarw.CaSO.sub.3+1/2H.sub.2O (7)
[0023] Furthermore, reaction shown in the following formula (8) is
undergone by reacting with 1/2 O.sub.2 in the above formula (4) and
O.sub.2 of excess air in the processed gas.
CaSO.sub.3+1/2O.sub.2+H.sub.2O.fwdarw.CaSO.sub.4.2H.sub.2O (8)
[0024] Besides, a desulfurizer for harmful gas described in
Japanese Patent No. 4418987 is provided with installation of a
basket-shaped rotation cylinder which is supported rotatably around
a horizontal shaft in a fixed duct and inside of which gas-liquid
contact fillers is filled, a slurry storage tank located below of
the basket-shaped rotation cylinder, and a back-flow means for
pumping up absorbent slurry in the slurry storage tank and flowing
back it to an outer peripheral surface of the basket-shaped
rotation cylinder. In the desulfurizer for harmful gas, since the
basket-shaped rotation cylinder can be rotated only by flowing the
absorbent slurry back, an electrical driving means for the
basket-shaped rotation cylinder can be unneeded, it is possible to
minimize the device and to reduce electrical consumption.
[0025] Recently, it is said that carbon dioxide gas that causes
global heating because of smoke exhausted from factories or power
plants must be recovered. And, as a previous step of recovering the
carbon dioxide gas from the exhaust smoke, though a FGD equipment
for removing sulfur dioxide from the exhaust smoke is used, not
only low-cost but also high-performance (approximately 100%
desulfurization) is required.
[0026] Furthermore, Japanese Patent No. 4505041 by the present
inventors is shown as a patent invention in relation with it.
SUMMARY OF THE INVENTION
[0027] However, there is a possibility that desulfurization is
decreased in the FGD equipment described in Japanese utility model
publication No. sho 53-19171.
[0028] Namely, in the FGD equipment described in Japanese utility
model publication No. sho 53-19171, in the case that amount of
oxygen in the processed gas, calcium sulfite can be oxidized by
oxygen in the processed gas to produce gypsum. However, in the case
that amount of oxygen in the processed gas is little, the equipment
has no means for taking oxygen into the equipment, so that
gypsumization reaction does not proceed sufficiently. In this case,
gypsumization becomes possible if the operation is carried out in
an acid condition by decreasing pH of drainage of the equipment,
but for it, it is necessary to work by decreasing a feed of
limestone slurry from theoretical requirement, and limestone
becomes insufficient with the desulfurization decreasing.
[0029] On the other hand, in the desulfurization equipment
described in Japanese patent No. 4418987, though it is possible to
take a means for supplement want of oxygen amount in the processed
gas by blowing new air into the circulating slurry, for increasing
the effectiveness, it has been necessary to form flow of the
absorbent slurry so as to acidize strongly in a slurry outlet side
(a gas introducing inlet side) and to basify strongly in a slurry
inlet side (a gas outlet side).
[0030] Besides, also in the desulfurization equipment described in
Japanese patent No. 4418987, desulfurization has a tendency to
decrease by want of the limestone slurry.
[0031] A problem of the present invention is to make the calcium
sulfite to gypsum at approximately 100% and to make the
desulfurization approximately 100%.
[0032] To resolve the above problem, flue-gas desulfurization (FGD)
equipment according to a first invention is characterized by being
provided with a fixing duct formed with a specific length having a
gas introduction inlet at one side and a gas discharge outlet at
another side; a basket-shaped rotation cylinder formed
approximately cylindrically whose both end surfaces and a
peripheral surface are formed in reticulated or lattice pattern,
wherein the end surface at one side faces the gas introduction
inlet and the end surface at another side faces the gas discharge
outlet, and which is located in the fixing duct in the condition of
being supported rotatably around a horizontal shaft; a rotation
packed bed which is constituted of filling fillers for gas-liquid
contact in the basket-shaped rotation cylinder and through which
gas introduced from a gas introduction inlet flows in an axial
direction thereof; gas shield plates arranged at a gas introduction
inlet side and a gas discharge outlet side of the rotation packed
bed; a slurry storage tank located below the rotation packed bed
and having plural communication storage sections which are divided
by partition plates each of which has a communication part at a
portion thereof; a slurry feed means for feeding absorbent slurry
to a gas discharge outlet side in the slurry storage tank; a slurry
discharge means for discharging the absorbent slurry from a gas
introduction side in the slurry storage tank; and slurry spray
means which are provided in response to the plural communication
storage sections respectively and each of which sprays the
absorbent slurry extracted from the corresponding communication
storage section to an upper part of the communication storage
section of the rotation packed bed, wherein the plural
communication storage sections are arranged so as to line up along
the axial direction, and wherein the absorbent slurry which is fed
to the gas discharge outlet side in the slurry storage tank by the
slurry feed means moves through the plural communication storage
sections to the gas introduction inlet side with desulfurization
and gypsumization and discharges from the gas introduction inlet
side in the slurry storage tank.
[0033] In the FGD equipment according to the first invention, the
plural communication storage sections are provided so as to line up
along the axial direction in the slurry storage tank. And, the
absorbent slurry fed to the gas discharge outlet side in the slurry
storage tank moves through the plural communication storage
sections to the gas introduction inlet side with desulfurization
and gypsumization and discharges from the gas introduction inlet
side in the slurry storage tank.
[0034] Thus, as compared to pH values of the absorbent slurry
stored in the communication storage sections respectively, the
closer the communication storage section of the plural
communication storage sections is positioned to the gas discharge
outlet side, the stronger basic of the absorbent slurry stored in
the corresponding communication storage section is, and the closer
the communication storage section of the plural communication
storage sections is positioned to the gas introduction inlet side,
the stronger acid of the absorbent slurry stored in the
corresponding communication storage section is.
[0035] Accordingly, as compared to pH values of absorbent slurry
spayed to parts of the rotation packed bed respectively, the closer
the part in the gas discharge outlet side, the stronger basic of
the absorbent slurry spayed to the corresponding part is, and the
closer the part is to the gas introduction inlet side, the stronger
acid of the absorbent slurry spayed to the corresponding part
is.
[0036] Thus, because pH value of the absorbent slurry discharged
from the gas introduction inlet side is decreased to be able to be
acidic, so that gypsumization of calcium sulfite can be carried out
more surely. This gypsumization is made surely by air blown into
the slurry storage tank, so that acid level of gypsum slurry
discharged from the gas introduction inlet side can be
decreased.
[0037] Accordingly, due to the FGD equipment according to the first
invention, calcium sulfite in the byproduct can be gypsumized at
approximately 100% and its desulfurization rate can be made at
approximately 100%.
[0038] Here, the slurry feed means according to the first invention
corresponds to a slurry feeder 62 as described below, the slurry
discharge means corresponds to a slurry discharge device 64 as
described below, and the slurry spray means corresponds to a
circulation device 63 as described below.
[0039] Flue-gas desulfurization (FDG) equipment according to a
second invention is characterized by, in the FDG equipment
according to the first invention, providing with an independent
storage section divided by a separation plate without the
communication part in the slurry storage tank; a liquid level
control means for feeding absorbent slurry to the independent
storage section so as to hold a specific liquid level thereof; and
a slurry spay means for spraying the absorbent slurry extracted
from the independent storage section to an upper part of the
independent storage section in the rotation packed bed, wherein the
independent storage section is positioned at the gas discharge
outlet side of the plural communication storage sections, wherein
the slurry feed means feeds the absorbent slurry extracted from the
independent storage section to the communication storage section of
the plural communication storage sections positioned the closest to
the gas discharge outlet side, so that feed of the absorbent slurry
can be controlled.
[0040] In the FDG equipment according to the second invention, the
independent storage section without communication to the
communication storage sections is provided on the gas discharge
outlet side of the plural communication storage section. And, the
absorbent slurry is fed to the independent storage section so that
the liquid level of the absorbent slurry in the independent storage
section.
[0041] Thus, the absorbent becomes more excess in the absorbent
slurry stored in the independent storage section positioned closer
the gas discharge outlet side than the plural communication storage
sections. Accordingly, the absorbent slurry with a state of more
excess absorbent is sprayed to an upper part (a part closest the
gas discharge outlet side) of the independent storage section in
the rotation packed bed. Therefore, even if the feed of the
absorbent slurry is decreased, it is possible to make the
desulfurization approximately 100%.
[0042] For instance, when four communication storage sections
a.about.d and one independent storage section e (total five storage
sections) are provided in the slurry storage tank, the absorbent
slurry stored in the communication storage section a that is
positioned the closest the gas introduction inlet side becomes
acid.about.neutrality, the absorbent slurry stored in the
communication storage sections b.about.d that are positioned closer
the gas discharge outlet side than the communication storage
section a becomes basic, and the absorbent (limestone) is in the
most excess in the absorbent slurry stored in the independent
storage section e that is positioned the closest the gas discharge
outlet side. And, in this state, the absorbent slurry stored in
every communication storage section a.about.e is sprayed and
circulated to the upper part of every storage section a.about.e in
the rotation packed bed.
[0043] In this case, feed of the absorbent slurry fed to the
communication storage section d positioned secondarily from the gas
discharge outlet side of the five storage sections a.about.e is
controlled so that gypsum slurry discharged from the gas
introduction inlet side becomes acidic (pH 3.about.6).
[0044] Here, if the feed of the absorbent slurry is a theoretical
feed 95% calculated from processed gas quantity and concentration
of the sulfur dioxide, desulfurization rate of the gas in the part
where is from the above of the communication storage section a to
the above of the communication storage section d becomes
approximately 95% by lack of the absorbent. However, residual 5% of
the sulfur dioxide acid gas is desulfurized in the upper part of
the independent storage section e in the rotation packed bed by
that the independent storage section e where the absorbent slurry
with a much excess state of the absorbent is sprayed is arranged at
the gas discharge outlet side of the communication storage section
d. Thus, in a whole of the rotation packed bed, approximately 100%
of the desulfurization rate can be achieved.
[0045] Accordingly, due to the FGD equipment according to the
second invention, calcium sulfite in the byproduct can be
gypsumized at approximately 100% and desulfurization rate thereof
can be made approximately 100%.
[0046] Due to the FGD equipment according to the present invention,
pH value of the absorbent slurry (gypsum slurry) discharged from
the gas introduction inlet side is decreased to be able to be
acidic, and gypsumization of the calcium sulfite can be performed
more surely. Furthermore, the gypsumization function becomes more
surely by the air blown into the slurry storage tank, so that
acidic level of the gypsum slurry can be decreased.
[0047] Besides, due to the FGD equipment according to the present
invention, desulfurization rate can be made approximately 100% by a
mechanism explained the former paragraphs.
[0048] Namely, due to the FGD equipment according to the present
invention, it is possible to gypsumize the calcium sulfite in the
byproduct at approximately 100% and it is possible to make the
desulfurization rate approximately 100%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 is a cross-sectional view of the flue-gas
desulfurization equipment according to one embodiment of the
invention;
[0050] FIG. 2 is a plan view of a slurry storage tank equipped by
the flue-gas desulfurization equipment shown in FIG. 1; and
[0051] FIG. 3 is a cross-sectional view cut along A-A line shown in
FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0052] Hereinafter, flue-gas desulfurization equipment 1 according
to an embodiment of the invention is explained by referring the
drawings.
[0053] The flue-gas desulfurization (FGD) equipment 1 is equipment
that installed on a flue-gas route of a factory, a power plant or
the like and removes sulfur dioxide from discharged flue-gas
(processed gas).
[0054] Especially, it is very advantageous that the FGD equipment
is installed before carbon dioxide gas recovery equipment for
recovering carbon dioxide from the flue-gas.
[0055] (Constitution of the FGD Equipment)
[0056] FIG. 1 is a cross-sectional view of the FGD equipment
according to the embodiment of the present invention. FIG. 1 shows
a state cutting the FGD equipment in the vertical direction along a
horizontal shaft 21 of a basket-shaped rotation cylinder 20.
Besides, in FIG. 1, flow of circulating absorbent slurry is
indicated by solid arrows and flow of processed gas is indicated by
dashed arrows.
[0057] FIG. 2 is a plan view of a slurry storage tank 40 equipped
by the FGD equipment 1. Especially, FIG. 2 shows arrangement of
separation plates 43, 44 in the slurry storage tank 40, the flow of
the absorbent slurry is indicated by the solid arrows and the flow
of the processed gas is indicated by the dashed arrows.
[0058] FIG. 3 is a cross-sectional view along A-A line shown in
FIG. 1. FIG. 3 shows a state that one of gas seal plates 50 is seen
from a direction along the horizontal shaft 21 of the basket-shaped
rotation cylinder 20.
[0059] The FGD equipment 1 shown in FIG. 1 is provided with a
fixing duct 10, the basket-shaped rotation cylinder 20 arranged in
the fixing duct 10, a rotation packed bed 30 formed in the
basket-shaped rotation cylinder 20, the slurry storage tank 40
located below the rotation packed bed 30, a pair of the gas seal
plates 50, and a slurry circulation system 60 for circulating the
absorbent slurry.
[0060] The fixing duct 10 is formed with a specific length and
arranged along horizontal direction. The fixing duct 10 has an
inner space possible to install the basket-shaped rotation cylinder
20 therein by expanding a central part down below and in a
front-back direction (depth direction shown in FIG. 1). The fixing
duct 10 has a gas introduction inlet 11 provided at one side in
processed gas flowing direction (horizontal direction shown in FIG.
1) and a gas discharge outlet 12 provided at another side in the
processed gas flowing direction. Besides, a mist separator 13 is
provided on the gas discharge outlet 12.
[0061] The basket-shaped rotation cylinder 20 is formed in
cylindrical basket-shape. Besides, the basket-shaped rotation
cylinder 20, especially a whole including the both end surfaces and
a peripheral surface is formed in a reticulated or lattice pattern.
In this embodiment, the both end surfaces and a peripheral surface
are formed in the reticulated or lattice pattern at approximately
60 mm intervals in order to fill fillers for gas-liquid contact
with 75 mmo.times.75 mm mmo. The basket-shaped rotation cylinder
20, whose end surface at one side faces the gas introduction inlet
11 side and whose end surface at another side faces the gas
discharge outlet 12 side, is arranged rotatably around the
horizontal shaft 21 inserted into a pair of bosses 22a, 22b. One
end of the horizontal shaft 21 is located at the gas introduction
inlet 11 side and another end of it is located at the gas discharge
outlet 12 side, so that the horizontal shaft 21 is supported
rotatably by three bearings 23a, 23b and 23c.
[0062] Furthermore, the basket-shaped rotation cylinder 20 is
rotated and driven around the horizontal shaft 21 by a geared motor
24. Rotation rate of the basket-shaped rotation cylinder 20 is
approximately 5 rpm.
[0063] Besides, this embodiment is constituted of that the
basket-shaped rotation cylinder 20 is rotated by the geared motor
24, but it may be also constitution that the basket-shaped rotation
cylinder 20 is rotated by a water wheel principle using weight of
the absorbent slurry sprayed above the rotation packed bed 30
instead of the geared motor 24 (seeing Japanese patent publication
No. 4418987).
[0064] The rotation packed bed 30 is formed by filling many fillers
for gas-liquid contact in the basket-shaped rotation cylinder 20.
As fillers for gas-liquid contact, what can form many interspaces
in the basket-shaped rotation cylinder 20, such as plastic
cylindrical members, Raschig rings, pole rings, net rings or the
like are used. Thus, the rotation packed bed 30 can make the gas
introduced from the gas introduction inlet 11 pass along the axial
direction (direction that the horizontal shaft 21 extends).
[0065] The slurry storage tank 40 is arranged at a bottom part of
the fixing duct 10 and located below the rotation packed bed 30.
The slurry storage tank 40 is formed in a box shape whose upper
part is opened and so as to be able to storage and circulate the
absorbent slurry. Here, in this embodiment, limestone is used as an
absorbent and limestone slurry is used as the absorbent slurry.
[0066] As shown in FIGS. 1 and 2, plural (four in this embodiment)
communication storage sections 41a.about.41d divided by partition
plates 43 each of which has a communication portion 43a in a part
thereof and an independent storage section 42 divided by a
partition plate without the communication portion are provided in
the slurry storage tank 40. The four communication storage sections
41a.about.41d and the independent storage section 42 are arranged
so as to line up along the axial direction (the direction that the
horizontal shaft 21 extends). Concretely, the communication storage
section 41a is located the closest the gas introduction inlet 11
side, the communication storage sections 41b, 41c and 41d are
located in series from the gas introduction inlet 11 side to the
gas discharge outlet 12 side, and the independent storage section
42 the closest the gas discharge outlet 12 side. Furthermore, the
absorbent slurry can be flown in or out between neighboring
communication storage sections 41a.about.41d via the communication
parts 43a of the separation plates 43 respectively. On the other
hands, the independent storage section 42 is not communicated with
the next communication storage section 41d.
[0067] As shown in FIGS. 1 and 3, gas seal plates are arranged on
the gas introduction inlet 11 side and the gas discharge outlet 12
side respectively. Each of the gas seal plates 50 is formed in an
approximately square plate and a circular through hole is provided
in a center portion thereof. Diameter of the through hole of the
gas seal plate 50 is smaller than diameter of the basket-shaped
rotation cylinder 20 (the rotation packed bed 30). The gas seal
plates 50 are arranged in a state that lower end parts thereof are
inserted into the liquid of the absorbent slurry stored in the
slurry storage tank 40, so that they seal between the basket-shaped
rotation cylinder 20 (rotation packed bed 30) and an inner surface
of the fixing duct 10, respectively.
[0068] The slurry circulation system 60 is provided with a liquid
level control device 61, a slurry feeder 62, circulation devices
63, a slurry discharge device 64 and an air blowing device 65.
[0069] The liquid level control device 61 is provided with a
limestone slurry feed pipe 61a and a slurry feed means (not shown
in figures) for feeding the absorbent slurry (limestone slurry) to
the independent storage section 42 via the limestone slurry feed
pipe 61a. The liquid level control device 61 feeds the absorbent
slurry to the independent storage section 42 so as to hold a
specific liquid level.
[0070] The slurry feeder 62 feeds the absorbent slurry to the gas
discharge outlet 12 side in the slurry storage tank 40. Concretely,
the slurry feeder 62 feeds the absorbent slurry extracted from the
independent storage section 42 to the communication storage section
41d which is positioned the closest the gas discharge outlet 12
side of the plural communication storage sections 41a.about.41d. At
this case, the slurry feeder 62 can control the feed of the
absorbent slurry.
[0071] The circulation devices 63 have slurry spray devices 63a for
spraying the absorbent slurry to the rotation packed bed 30, pipes
63b connecting the slurry spray devices and the slurry storage tank
40, circulation pumps 63c for pumping the absorbent slurry stored
in the slurry storage tank 40 to the slurry spray devices 63a via
the pipes 63b, respectively.
[0072] Here, the slurry spray device 63a may be constitution of
spraying the absorbent slurry by a spray nozzle, or may be
constitution of flowing down the absorbent slurry from a top end of
the pipe, and they are not limited.
[0073] In the present embodiment, the circulation devices 63
corresponding to the four communication storage sections
41a.about.41d and the independent storage section 42 respectively
(total five circulation devices 63) are provided. Concretely, in
the present embodiment, five slurry spray devices 63a, five pipes
63b and five circulation pumps 63c (Pa, Pb, Pc, Pd, Pe shown in
FIG. 1) are provided. Here, in FIG. 1, symbols a.about.e are marked
below the circulation pumps 63c, above the pipes 63b and above the
slurry spray devices 63a respectively, but theses indicate that the
circulation pumps 63a, pipes 63b and the slurry spray devices 63a
that the same symbols a.about.e are marked are connected.
Furthermore, the circulation devices 63 spray the absorbent slurry
extracted from the corresponding storage sections 41a.about.41d and
42 to the upper parts of the corresponding storage sections
41a.about.41d and 42 in the rotation packed bed 30,
respectively.
[0074] The slurry discharge device 64 has a gypsum slurry discharge
pipe 64a and a valve 64b provided on the gypsum slurry discharge
pipe 64a. The slurry discharge device 64 discharges the absorbent
slurry (gypsum slurry) from the gas introduction inlet 11 side in
the slurry storage tank 40. Concretely, the slurry discharge device
64 discharges the absorbent slurry (gypsum slurry) from the
communication storage section 41a the closest the gas introduction
inlet 11 side of the plural communication storage sections
41a.about.41d. In this case, the slurry discharge device 64 can
control the liquid level of every communication storage sections
41a.about.41d by controlling discharge amount of the absorbent
slurry.
[0075] The air blowing device 65 can blow air into the liquid of
the absorbent slurry stored in the four communication storage
sections 41a.about.41d and the independent storage section 42
respectively.
[0076] (Control of the FGD Equipment)
[0077] Next, control of the FGD equipment is explained.
[0078] Feed of the absorbent slurry into the slurry storage tank 40
by the liquid level control device 61 is controlled so that height
of liquid surface of the absorbent slurry in the independent
storage section 42 positioned at the gas discharge outlet 12 side
becomes a specific height.
[0079] Feed of the absorbent slurry into the communication storage
section 41d by the slurry feeder 62 is controlled so that pH value
of the absorbent slurry discharging from the communication storage
section 41a positioned at the gas introduction inlet 11 side
becomes within 3.about.6.
[0080] In this case, in order to make the absorbent slurry be
acidic, amount of the absorbent (limestone) contained in the
absorbent slurry becomes insufficient against a theoretical
requirement calculated from amount of the processed gas and
concentration of sulfur dioxide. Thus, desulfurization rate of the
processed gas in a part from the upper part of the communication
storage section 41a to the upper part of the communication storage
section 41d becomes approximately 95% because of want of the
limestone. However, because the independent storage section 42 that
stores the absorbent slurry which is in much excess of the
absorbent is arranged the closest the gas discharge outlet 12 side
of the five storage sections 41a.about.41d and 42, the absorbent
slurry with much excess of the absorbent is sprayed to a part the
closest the gas discharge outlet 12 side in the rotation packed bed
30, so that residue 5% of the sulfur dioxide is desulfurized in
this part. Thus, approximately 100% of desulfurization rate can be
achieved in a whole of the rotation packed bed 30.
[0081] Liquid level of the absorbent slurry in the slurry storage
tank 40 (the communication storage sections 41a.about.41d) is
controlled by controlling on/off of the valve 64b in the slurry
discharge device 64.
[0082] (Function of the FGD Equipment)
[0083] Next, a function of the FGD equipment is explained.
[0084] IN the FGD equipment, the processed gas is blown from the
gas introduction inlet 11 into the fixing duct 10 by a blower not
shown in figures, passes through the basket-shaped rotation
cylinder 20 (the rotation packed bed 30) arranged in the center of
the fixing duct 10, and is discharged from the gas discharge outlet
12 after the mist separator 13.
[0085] On the other hand, in the slurry storage tank 40, the slurry
feeder 62 feeds the absorbent slurry extracted from the independent
storage section 42 to the communication storage section 41d
positioned the closest the gas discharge outlet 12 side of the
plural communication storage sections 41a.about.41d. And the
absorbent slurry fed from the gas discharge outlet 12 side (the
communication storage section 41d) in the slurry storage tank 40
moves via the plural communication storage sections 41a.about.41d
to the gas introduction inlet 11 side with desulfurization and the
gypsumization, and is discharged from the gas introduction inlet 11
side (the communication storage section 41a) via the plural
communication storage sections 41a.about.41d.
[0086] In this case, the absorbent slurry stored in every storage
sections 41a.about.41d and 42 is sprayed in the basket-shaped
rotation cylinder 20 by the circulation devices 63 that is provided
corresponding to the storage sections 41a.about.41d and 42.
[0087] The absorbent slurry sprayed in the basket-shaped rotation
cylinder 20 is flown down on surfaces of the fillers for gas-liquid
contact with being influenced by gravity of the absorbent slurry
flowing down in the basket-shaped rotation cylinder 20 and rotation
of the basket-shaped rotation cylinder 20, and flown down to the
every storage sections 41a.about.41d and 42 of slurry storage tank
40 with reacting by gas-liquid contact with a wider area that
slurry liquid film formed in this time comes in contact with the
processed gas passing through the fixing duct 10.
[0088] Furthermore, the absorbent slurry flown down the slurry
storage tank 40 contains a lot of gypsum produced in the reaction
by the gas-liquid contact with the reprocessed gas.
[0089] Besides, in the slurry storage tank 40, because the air
blowing device 65 blows air into the liquid of the absorbent
slurry, the absorbent slurry is stirred and fresh oxygen is
supplemented to resolve the limestone powder and to circulate the
absorbent slurry in turns.
[0090] As mentioned above, in the FGD equipment 1, the plural
communication storage sections 41a.about.41d and 42 are provided so
as to line up along the axial direction. And, the absorbent slurry
fed to the gas discharge outlet 12 side of the slurry storage tank
40 (the independent storage section 42) moves to the gas
introduction inlet 11 side via the plural communication storage
sections 41a.about.41d with the desulfurization and the
gypsumization, and discharges from the gas introduction inlet 11
side of the slurry storage tank 40 (the communication storage
section 41a).
[0091] Thus, as compared to pH values of the absorbent slurry
stored in the every communication storage sections, the closer the
communication storage section is positioned to the gas discharge
outlet 12 side in the plural communication storage sections, the
stronger basic of the absorbent slurry stored in the communication
storage section is, and the closer the communication storage
section is positioned to the gas introduction inlet 11 side in the
plural communication storage sections, the stronger acidity of the
absorbent slurry stored in its communication storage section
is.
[0092] Accordingly, as compared to pH value of the absorbent slurry
sprayed in every part in the rotation packed bed 30, the closer to
the gas discharge outlet 12 side, the stronger basic of the
absorbent slurry spayed to the part is, and the closer to the gas
introduction inlet 11 side, the stronger acidity of the absorbent
slurry sprayed to the part is.
[0093] Thus, the pH value of the absorbent slurry (gypsum slurry)
discharged from the gas introduction inlet 11 side can be decreased
to be acidic, and gypsumization of calcium sulfite can be performed
more surely. This gypsumization action is made more surely by the
air blown into the slurry storage tank 40, so that acidic level of
the gypsum slurry discharged from the gas introduction inlet 11
side can be weakened.
[0094] Especially, the absorbent slurry stored in the independent
storage section 42 positioned closer to the gas discharge outlet 12
side than the plural communication storage section 41a.about.41d is
in a state of much excess of the absorbent. Accordingly, the
absorbent slurry with much excess of the absorbent is sprayed an
upper part of the independent storage section 42 (a part positioned
the closest to the gas discharge outlet 12 side) in the rotation
packed bed 30.
[0095] Here, if the feed of the absorbent slurry is set to 95% of
theoretical feed calculated from amount of the processed gas and
concentration of the sulfur dioxide, desulfurization rate of the
gas in a part from the upper part of the communication storage
section 41a to the upper part of the communication storage section
41d in the rotation packed bed 30 becomes approximately 95% due to
want of the absorbent. However, because the independent storage
section 42 where the absorbent slurry with much excess of the
absorbent is located at the gas discharge outlet 12 side in the
communication storage section 41d, residue 5% of the sulfur dioxide
is desulfurized in the upper part of the independent storage
section 42. Thus, in a whole of the rotation packed bed 30,
approximately 100% of the desulfurization rate can be achieved.
[0096] Next, a working example of the FGD equipment is
explained.
[0097] Test models 1.about.4 of the FGD equipment by
limestone-gypsum method with 100% of desulfurization were produced
experimentally based on data of the embodiments of the FGD
equipment described in the Japanese utility model publication No.
sho 53-19171 (the prototype machine with 1 m diameter of the
rotation packed bed, the first practical machine with 3.2 m
diameter of the rotation packed bed, the second practical machine
with 4.5 m diameter of the rotation packed bed, and the third
practical machine with 4.5 m diameter of the rotation packed
bed).
[0098] The result of every test model is shown in Table 2.
TABLE-US-00002 TABLE 2 Test Test Test Test Model 1 Model 2 Model 3
Model 4 Gas Throughput (Nm.sup.3/h) 200,000 500,000 1,000,000
3,000,000 ConcenTration of sulfur dioxide in the 1,000 1,000 1,000
1,000 gas introduction inlet (ppm) Diameter of the basket-shaped
rotation 6.2 9.9 14.0 24.3 cylinder (m) Length of the basket-shaped
rotation 3 3 3 3 cylinder (m) Rotation rate of the basket-shaped 5
5 5 5 rotation cylinder (rpm) Maximum area of the slurry dropping
part 6.2 .times. 3.0 9.9 .times. 3.0 14.0 .times. 3.0 24.3 .times.
3.0 (m.sup.2) Volume of the circulating pump (m.sup.3/h) 930 1495
2100 3645 (Pa + Pb + Pc + Pd + Pe) Desulfurization rate (%) 100 100
100 100 Byproduct gypsum gypsum gypsum gypsum Pump required head
(m) 10 15 20 30 Loss of draft pressure (mm) less than 200 less than
200 less than 200 less than 200 Slurry amount per unit area 50
m.sup.3/m.sup.2h 50 m.sup.3/m.sup.2h 50 m.sup.3/m.sup.2h 50
m.sup.3/m.sup.2h
[0099] In a journal "Thermal and Nuclear Power Generation", No. 2
thermal power plant in Matsuura (J-Power) and No. 1 thermal power
plant in Hitachinaka (TEPCO) are introduced as equipment of
3,000,000 Nm.sup.3/h class, there is description such that:
in the case of Matsuura thermal power No. 2, Circulation Pump: 72.5
m.sup.3/min.times.12 Ventilator: 39,200 m.sup.3/min.times.560 mmAq
in the case of Hitachinaka No. 1, Circulation Pump: 127.5
m.sup.3/min.times.5.
[0100] Calculating this, amount of slurry circulation is 52,200
m.sup.3/h in the former and 38,250 m.sup.3/h in the latter.
[0101] As compared these figures to the test model 4, the result
becomes shown in Table 3.
TABLE-US-00003 TABLE 3 Amount of slurry circulation Rate J-Power
Matsuura 52,200 14.3 TEPCO Hitachinaka 38,250 10.5 Present
Invention 3,645 1 (Test model 4)
[0102] As shown in Table 3, there is large difference in the amount
of slurry circulation between the case of the present invention and
the case of J-power Matsuura or TEPCO Hitachinaka.
[0103] The FGD equipment by the limestone-gypsum method used in
Japan is a spray tower system mainly, but it is not what prepares a
means for ensuring 100% desulfurization, and there is disadvantage
that energy consumption is large since the amount of slurry
circulation by the circulation pump is extraordinary large as shown
in Table 3 and loss of the draft pressure is large.
[0104] In contrast, due to the FGD equipment according to the
present invention, the amount of the slurry circulation can be
decreased and length of the rotation cylinder is short, so that the
draft pressure can be decreased and it is possible to control the
energy consumption.
* * * * *